JP5108601B2 - Glow plug with combustion pressure sensor - Google Patents

Description

  The present invention relates to a glow plug with a combustion pressure sensor used for an internal combustion engine such as an automobile engine.

  2. Description of the Related Art Conventionally, a glow plug with a combustion pressure sensor provided with a combustion pressure sensor for detecting the combustion pressure of the internal combustion engine is known as a glow plug used in an internal combustion engine such as a diesel engine for automobiles.

In such a glow plug with a combustion pressure sensor, by providing the pressure detection element closer to the tip end in the axial direction closer to the combustion chamber, it is possible to reduce the influence of noise due to vibration, etc., and to increase the combustion pressure with higher accuracy. Can be detected. For this reason, for example, a glow plug with a combustion pressure sensor in which a pressure detection element is provided so as to be located in a position adjacent to the axial rear end side end portion of the heater in the housing is known (for example, Patent Documents). 1). Further, it is known to use a piezoresistive element as a pressure detecting element for detecting such combustion pressure (see, for example, Patent Document 2).
JP 2007-292415 A Japanese Patent No. 3166015

  As described above, in the glow plug with a combustion pressure sensor, the pressure detection element is arranged at a position as close to the combustion chamber as possible, such as a position adjacent to the rear end side end of the heater. However, on the rear end side of the heater in the housing, as a power supply conductive member for supplying power to the heater, for example, a metal rod-like member called a central shaft or the like is disposed. For this reason, it is necessary to provide a pressure detection element and a pressure detection element mounting member for mounting the pressure detection element in the housing, avoiding the position of the central shaft, which hinders the downsizing of the glow plug with the combustion pressure sensor. There was a problem of becoming.

  Further, as a method for detecting combustion pressure with high accuracy by reducing noise of the pressure detection element as described above, a method of assembling a Wheatstone bridge in which four resistors are arranged in a bridge shape in the pressure detection element is also known. . However, when such a Wheatstone bridge is used, there are four output lines from the pressure detection element, so a space for arranging signal transmission conductive members such as four wires is required in the housing. However, there has been a problem that the glow plug with a combustion pressure sensor hinders downsizing.

  The present invention has been made to solve the above problems. An object of the present invention is to provide a glow plug with a combustion pressure sensor that can detect combustion pressure with high accuracy and can be downsized.

The glow plug with a combustion pressure sensor of the present invention has a cylindrical housing, a pressure detecting element arranged in the housing, a front end side protruding from a front end portion of the housing, and a rear end side accommodated in the housing. A heater having a tip end surface as a pressure receiving surface, a heater for transmitting a combustion pressure to the pressure detecting element, an axially rear end side of the heater in the housing and the heater A power supply conductive member connected to the heater directly or via another member for supplying power to the heater, wherein the pressure detection element is disposed and orthogonal to the central axis of the heater provided, the heater by comprising a power supply conductive member having a pressure sensing element mounting portion distorted by the combustion pressure transmitted, the power supply conductive portion However, the pressure detection element mounting portion on which the pressure detection element is disposed, and the central axis direction of the heater from the back side central portion on the opposite side of the pressure detection element mounting portion on the side on which the pressure detection element is disposed A rod-shaped portion protruding to the periphery of the pressure-sensing element mounting portion, and distorting the pressure-sensing element-mounting portion by applying a combustion pressure transmitted by the heater between a peripheral portion of the pressure-sensing element mounting portion and the rod-shaped portion. Features.

  In the glow plug with a combustion pressure sensor of the present invention, the power supply conductive member for supplying power to the heater has a pressure detection element mounting portion that is disposed with the pressure detection element and is distorted by the combustion pressure transmitted by the heater. The pressure detection element is mounted here. Therefore, it is not necessary to provide a pressure detection element mounting member in the housing separately from the power supply conductive member, and the glow plug with the combustion pressure sensor can be downsized by reducing the number of components. In addition, since the pressure detection element mounting portion is provided so as to be orthogonal to the central axis of the heater, the pressure detection element is disposed so as to be positioned in the housing adjacent to the end portion on the rear end side in the axial direction of the heater. The combustion pressure can be detected with high accuracy by reducing the influence of noise caused by vibration. Furthermore, since the combustion pressure is detected when the pressure detection element mounting portion is distorted, the combustion pressure transmitted by the heater is not directly applied to the pressure detection element, and damage to the pressure detection element can be prevented.

  In the glow plug with a combustion pressure sensor configured as described above, the conductive member for power supply includes a pressure detection element mounting portion on which the pressure detection element is disposed and a side on which the pressure detection element is disposed on the pressure detection element mounting portion. A bar-shaped portion protruding in the central axis direction of the heater from the opposite rear side central portion, and pressure is applied by applying the combustion pressure transmitted by the heater between the peripheral portion of the pressure-detecting element mounting portion and the rod-shaped portion It is preferable that the detection element mounting portion is distorted. As a result, the pressure detecting element mounting portion can be efficiently distorted and the combustion pressure can be detected with high accuracy.

  In the glow plug with a combustion pressure sensor having the above configuration, the pressure detection element is preferably fixed to the pressure detection element mounting portion via an insulating material. Thus, it is possible to reliably prevent an electrical short circuit from occurring between the power supply conductive member and the pressure detection element. As this insulating material, glass can be preferably used.

In the glow plug with the combustion pressure sensor configured as described above, the pressure detecting element includes a piezoresistor, the piezoresistor is arranged so as to be point-symmetric with respect to the central axis of the heater, and all the piezoresistors are provided. It is preferable that the pressure detection element is arranged in the pressure detection element mounting portion so that the two are connected in series. As a result, noise generated by vibration can be canceled out by the piezoresistors disposed symmetrically with respect to the point, and the combustion pressure can be detected with high accuracy. In addition, since it is not necessary to use a Wheatstone bridge or the like, the number of signal transmitting conductive members can be less than four, and downsizing by reducing the diameter of the housing can be achieved.
In this case, the piezoresistors arranged so as to be point-symmetric with respect to the central axis of the heater are divided into two by a virtual line passing through the central axis of the heater and orthogonal to the central axis. It is preferable to make the sum of the resistance values of the body equal. As a result, noise generated by vibration can be more reliably canceled out by the piezoresistors arranged symmetrically, and the combustion pressure can be detected with high accuracy.

  In the glow plug with a combustion pressure sensor configured as described above, the housing has a seat surface that is in close contact with the engine on the front end side in the axial direction, and a screw portion for engine attachment on the outer peripheral surface on the rear end side in the axial direction from the seat surface. It is preferable that the pressure detection element is provided on the front end side in the axial direction from the screw portion for mounting the engine on the housing. Thereby, it can suppress that the noise based on a vibration is added to the detection signal of a pressure detection element.

  In the glow plug with a combustion pressure sensor having the above configuration, the pressure detection element is preferably arranged on the heater side of the pressure detection element mounting portion. As a result, the pressure detection element can be arranged on the more distal end side in the axial direction, and noise based on vibration can be prevented from being added to the detection signal of the pressure detection element.

  According to the glow plug with a combustion pressure sensor of the present invention, it is possible to provide a glow plug with a combustion pressure sensor that can detect the combustion pressure with high accuracy and can be downsized.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a glow plug 100 with a combustion pressure sensor according to an embodiment of the present invention. FIG. 1 (a) is a cross-sectional view showing the overall configuration of the glow plug 100 with a combustion pressure sensor, and FIG. ) Is a cross-sectional view showing an enlarged main part of the glow plug 100 with the combustion pressure sensor.

  As shown in FIG. 1, the glow plug 100 with a combustion pressure sensor is made of a high-strength metal such as carbon steel (S45C, etc.), stainless steel (eg, SUS430, SUS630, etc.), and is formed in a substantially cylindrical shape. A housing 1 is provided. A cap member 2 is provided at the tip of the housing 1 (the lower end in FIG. 1).

  As shown in FIG. 1A, a screw portion 4 for attaching the glow plug 100 with a combustion pressure sensor to an engine (engine) (not shown) is formed on the outer peripheral surface of the housing 1. A tool engaging portion 5 for engaging a tool such as a spanner or a wrench when the housing 1 is attached to the engine is provided on the outer peripheral portion on the rear end side (upper side in FIG. 1) from the screw portion 4.

  The cap member 2 has an opening 6 for allowing the heater 20 to protrude from the front end of the housing 1, and the end surface on the front end side in the axial direction is a seat surface that is in close contact with an engine such as an automobile diesel engine. (Tapered surface) 7 is formed. A heater support member 10 made of a metal such as stainless steel (for example, SUS430, SUS630, etc.) and formed in a substantially cylindrical shape is provided in the opening 6, and the heater 20 is provided inside the heater support member 10. Is provided. The heater 20 is composed of, for example, a ceramic heater (made of silicon nitride, alumina, or the like) in which a conductive ceramic is provided inside an insulating ceramic, or a metal glow heater (made of a coil, a stainless tube, insulating powder, or the like). ing. A tip surface 23 of the heater 20 shown in FIG. 1A is a pressure receiving surface that receives the combustion pressure in the combustion chamber.

  The heater support member 10 includes a housing connection portion 11 formed of a flange protruding outwardly in a bowl shape at a rear end portion thereof. Moreover, the inner peripheral part of this housing connection part 11 is made into the movable part 12 made thin. The movable portion 12 has a function of displacing the heater 20 in the axial direction by elastically deforming according to the combustion pressure applied to the pressure receiving surface of the heater 20. A heater connection portion 13 having a cylindrical shape is provided on the distal end side of the movable portion 12 of the heater support member 10. The heater connecting portion 13 is connected to the heater 20 by press-fitting or brazing. The heater connecting portion 13 is electrically connected to a ground side electrode (not shown) provided so as to be exposed on the outer peripheral surface of the heater 20, and the heater 20 connects the heater connecting portion 13 and the housing 1. To the ground potential.

  A cylindrical member 30 for holding a pressure detection element that extends in a cylindrical shape toward the rear end side is provided on the rear end side of the housing connecting portion 11 of the heater support member 10. On the tip end side in the axial direction of the cylindrical member 30 for holding the pressure detection element, a flange portion 31 that protrudes outwardly in a bowl shape is formed. And this flange part 31 and the above-mentioned housing connection part 11 of the heater support member 10 are fixed by welding or the like in a state of being interposed between the cap member 2 and the housing 1, thereby holding the pressure detection element. A cylindrical member 30 and a heater support member 10 are connected to the housing 1.

  An insulating plate 32 formed in a disc shape is fixed to a rear end side end portion of the pressure detecting element holding cylindrical member 30 by a cylindrical body 35 provided on the rear end side. A glow electrode through hole 33 is formed at the center of the insulating plate 32, and a plurality of (for example, two) elements having a smaller diameter than the glow electrode through hole 33 are formed around the glow electrode through hole 33. An electrode through-hole 34 is formed. In these element electrode through holes 34, element electrodes 41 for deriving a detection signal of the pressure detection element 40 are arranged. Therefore, the element electrode through holes 34 are provided corresponding to the number of element electrodes 41.

  A glow energizing electrode 50 made of a conductive member is fixed to the insulating plate 32. A disc-shaped first flange portion 51 is formed as a pressure detection element mounting portion at the tip side end portion of the glow energization electrode 50. A rod-like portion 56 that protrudes toward the rear end side is formed at the central portion on the rear end side of the first flange portion 51. Further, a second flange portion 52 having a smaller diameter than the first flange portion 51 is formed on the rear end side of the first flange portion 51 so as to protrude from the rod-like portion 56 in a bowl shape in the radial direction. ing. The glow energizing electrode 50 is fixed to the insulating plate 32 in a state where the second flange portion 52 is in contact with the surface on the front end side of the insulating plate 32, and the rod-shaped portion on the rear end side from the second flange portion 52. 56 is projected to the rear end side through the glow electrode through hole 33.

  The pressure detection element 40 is disposed on the surface of the first flange portion 51 of the glow energization electrode 50 on the tip side. The pressure detection element 40 is fixed to the surface on the distal end side of the first flange portion 51 via an insulating material such as glass. Further, the first flange portion 51 is provided with a plurality of through holes 53 corresponding to the above-described element electrode through holes 34, and the element electrodes 41 are disposed on the rear end side through the through holes 53. Has been pulled out. The through-hole 53 is filled with an insulating material such as glass, and the element electrode 41 and the glow energizing electrode 50 are electrically insulated.

  A ring-shaped member 54 is fixed to the peripheral edge of the first flange portion 51 of the glow energization electrode 50 by welding or the like. The front end side of the ring-shaped member 54 is fixed to the rear end side of the heater 20 and is electrically connected to a plus side electrode (not shown) provided so as to be exposed on the outer peripheral surface of the heater 20. , Constituting a part of the power supply path to the heater 20. The ring-shaped member 54 also functions as a pressure transmission mechanism. That is, when the heater 20 is displaced to the rear end side by the combustion pressure, the peripheral edge portion of the first flange portion 51 is pressed through the ring-shaped member 54. At this time, the central portion of the back side (rear end side) of the first flange portion 51 is supported by the rod-shaped portion 56, and the rod-shaped portion 56 is fixed to the insulating plate 32 via the second flange portion 52. Therefore, the peripheral edge portion of the first flange portion 51 is distorted so as to be displaced toward the rear end side. And the combustion pressure in a combustion chamber is detected by detecting the distortion of the 1st flange part 51 at this time with the pressure detection element 40. FIG.

  As described above, in the present embodiment, the first flange portion 51 of the glow energization electrode 50 is a pressure detection element mounting portion, and the pressure detection element 40 is disposed here. There is no need to provide a separate member for mounting the pressure detecting element 40, avoiding the arrangement position of. For this reason, the number of parts can be reduced and the glow plug 100 with a combustion pressure sensor can be reduced in size. Further, since the pressure detection element 40 can be provided at a position adjacent to the axial rear end side end of the heater 20, it is possible to detect the combustion pressure with high accuracy by reducing the influence of noise caused by vibration. .

  As described above, when the strain of the first flange portion 51 is detected by the pressure detection element 40, for example, a piezoresistive element can be used as the pressure detection element 40. FIG. 7 shows a configuration example when two piezoresistive elements 401 and 402 are used as the pressure detecting element 40. In FIG. 7, reference numeral 201 denotes a central axis passing through the axial center of the heater 20 described above, and the two piezoresistive elements 401 and 402 are arranged point-symmetrically with respect to the central axis 201 and are made of gold or the like. Are connected in series by a connecting wire 410 made of As shown in FIG. 7, there are two device electrodes 41 in this case.

  As described above, when noise due to vibration is generated by arranging a plurality of piezoresistive elements 401 and 402 in point symmetry with respect to the central axis 201 and connecting them in series, the noise components are converted into a plurality of noise components. This can be canceled by the change in resistance value of the piezoresistors R1 and R2 of the piezoresistive elements 401 and 402, and the combustion pressure can be detected with high accuracy. In this case, it is preferable that the sum of the resistance values of the piezoresistors on each side of the piezoresistors arranged so as to be point-symmetric is made equal. That is, in the example shown in FIG. 7, it is preferable that the resistance value of the piezoresistor R1 of the piezoresistive element 401 is equal to the resistance value of the piezoresistor R2 of the piezoresistive element 402. As a result, the absolute values of the changes in the resistance values of the piezoresistors on each side due to vibration are substantially equal, and noise generated by the vibrations is more reliably offset by the piezoresistors R1 and R2 arranged symmetrically. The combustion pressure can be detected with high accuracy. The above-mentioned “equal resistance value” includes the case where there is a difference in resistance value that is about the variation of the resistance value in the manufacturing process of a normal piezoresistor. It means to be about% or less.

  When the pressure detection element 40 is constituted by a piezoresistive element, for example, as shown in FIG. 8, one piezoresistive element 403 provided with two piezoresistors R1 and R2 symmetrically with respect to the central axis 201 is used. May be. Further, as shown in FIG. 9, one piezoresistive element 404 provided with one piezoresistor R in point symmetry with respect to the central axis 201 may be used. In the case of the piezoresistive element 404 in FIG. 9, it is equivalent to the case where two piezoresistors R1 and R2 (R1 + R2 = R) are connected in series symmetrically with respect to the central axis 201.

  When the pressure detection element 40 is configured as described above, noise due to vibration can be removed without using a Wheatstone bridge or the like. Moreover, as shown in FIGS. 7-9, since the element electrode 41 and the sensor terminal 42 mentioned later can be made into two (less than four), compared with the case where a Wheatstone bridge is used, the housing 1 has a small diameter. Can be reduced in size.

  As shown in FIG. 1, a glow energizing cylinder for supplying power to the heater 20 formed in a cylindrical shape from a conductive material such as a metal on the rear end side of the pressure detecting element holding cylindrical member 30. A member 55 is provided. The glow energization tubular member 55 is electrically connected to the glow energization electrode 50 on the tip side via a wire (not shown) such as a nickel wire. Further, the rear end side of the glow energizing tubular member 55 is electrically connected to the connector 8 provided at the rear end side end portion of the housing 1.

  Inside the glow energization cylindrical member 55, a sensor terminal 42 (conductive member for signal transmission) connected to the rear end portion of the element electrode 41 and the sensor terminal 42 are electrically connected to detect pressure. A signal processing circuit 43 for processing a detection signal from the element 40 is accommodated. The signal processing circuit 43 is configured by mounting an IC 45 or the like such as an ASIC (Application Specific Integrated Circuit) on a substrate 44. The IC 45 is arranged so as not to be on the tip side from the screw portion 4 of the housing 1. This prevents the IC 45 from being exposed to a high temperature due to heat from the combustion chamber, that is, the IC 45 is not exposed to a higher temperature atmosphere than the engine being cooled, to which the screw portion 4 is fastened. ing. An output signal of the signal processing circuit 43 is input to a control device such as an ECU via the connector 8 to detect a change in combustion pressure in the engine.

  Further, as shown in FIG. 2, an insulating material 46 made of glass, resin, or the like is filled between the sensor terminal 42 and the signal processing circuit 43 and the glow energizing tubular member 55. Thus, by filling the insulating material 46, it is possible to reliably prevent the sensor terminal 42, the signal processing circuit 43, and the glow energizing tubular member 55 from being electrically short-circuited.

  As described above, in the present embodiment, the glow energization tubular member 55 for supplying power to the heater 20 is tubular (cylindrical), and the detection signal from the pressure detection element 40 is taken out of the tubular member 55. The sensor terminal 42 is accommodated. Therefore, even when a large current for heating the heater 20 flows through the glow energizing tubular member 55, noise from the glow energizing tubular member 55 causes noise in the pressure detection element 40 flowing through the sensor terminal 42. The combustion pressure can be detected with high accuracy without entering the detection signal.

  Further, in the present embodiment, not only the sensor terminal 42 described above but also a signal processing circuit 43 for processing a detection signal from the pressure detection element 40 is accommodated in the glow energizing cylindrical member 55. With this configuration, the combustion pressure can be detected with higher accuracy. That is, the detection signal output from the pressure detection element 40 is weak, and when noise enters the detection signal from the pressure detection element 40 before amplification, the S / N ratio is reduced and the combustion pressure is detected with high accuracy. However, once the detection signal is amplified, even if noise enters the amplified detection signal, compared to the case where noise enters the detection signal from the pressure detection element 40 before amplification, A decrease in the S / N ratio can be suppressed. By accommodating the signal processing circuit 43 in the glow energization tubular member 55, it is possible to more reliably prevent noise from entering the detection signal before amplification.

  In the glow plug 100 with the combustion pressure sensor configured as described above, the tip of the heater 20 protrudes from the tip of the housing 1 as shown in FIG. The glow plug 100 is inserted into a plug mounting hole of an engine (not shown), and the screw portion 4 is fastened to the mounting screw of the engine to bring the seat surface 7 into contact with the engine, thereby ensuring airtightness. In this state, the heater 20 is attached to the internal combustion engine so that the front end side is located in the combustion chamber, and the heater 20 is energized to generate heat, thereby assisting in starting the internal combustion engine.

  When combustion pressure is applied to the tip surface (pressure receiving surface) 23 of the heater 20, the movable portion 12 is elastically deformed (bent), so that the heater 20 is displaced in the axial direction toward the rear, and pressure detection. The peripheral edge portion of the first flange portion 51 of the glow energization electrode 50 in which the element 40 is disposed is pressed by the ring-shaped member 54. Since the central portion of the first flange portion 51 is substantially fixed to the housing 1 via the rod-like portion 56 of the glow energizing electrode 50 and the second flange portion 52 that extend to the rear end side, When the peripheral edge portion of the first flange portion 51 of the energizing electrode 50 is pressed, the peripheral edge portion is displaced to the rear end side, and the first flange portion 51 is distorted. This distortion is detected by the pressure detection element 40 as a pressure change. Is done.

  The output signal of the pressure detecting element 40 is transmitted to the signal processing circuit 43 through the sensor terminal 42 accommodated in the glow energizing tubular member 55 and amplified by the signal processing circuit 43.

  As the pressure detection element 40, an element configured from a piezoresistive element such as an Si element or an SOI element and configured to output an electric signal corresponding to strain when pressure is applied can be used. . When such a pressure detection element 40 is comprised, it can be set as the structure which joined elements, such as Si element and SOI element, to the board | substrate which consists of glass, a metal, etc. A piezoresistor is formed on the surface of the element, and pressure is detected from a change in resistance value when the element is strained and deformed. In addition, piezoelectric elements such as PZT and quartz can also be used.

  Next, a second embodiment will be described with reference to FIGS. FIG. 3 shows a configuration of a main part of a glow plug 200 with a combustion pressure sensor according to the second embodiment, and corresponds to the portion shown in FIG. 1B in the glow plug 100 with a combustion pressure sensor of FIG. 1 described above. .

  As shown in FIG. 3, in the glow plug 200 with a combustion pressure sensor, a disk-shaped first flange portion 151 is provided as a pressure detection element mounting portion on the rear end side end portion of the glow energization electrode 150 made of a conductive member. Is formed. A rod-like portion 156 that protrudes toward the front end side is formed at the center of the back side (front end side) of the first flange portion 151. Further, a disc-shaped second flange portion 152 is formed at the end of the rod-shaped portion 156 on the front end side, and the first flange portion 151 and the second flange portion 152 are connected by the rod-shaped portion 156. The cross-sectional shape is configured to be substantially letter-shaped.

  The peripheral edge portion of the first flange portion 151 is fixed to an annular insulating member 132 by brazing or the like, and the insulating member 132 is fixed to the pressure detection element holding cylindrical member 30 by brazing or the like. ing. Therefore, the peripheral edge portion of the first flange portion 151 is fixed to the housing 1 via the insulating member 132 and the pressure detection element holding cylindrical member 30. In addition, the pressure detection element 40 is disposed on the rear end surface of the first flange portion 151. The pressure detection element 40 is fixed to a surface on the rear end side of the first flange portion 151 via an insulating material such as glass.

  4 shows the electrical connection between the pressure detecting element 40 and the glow energizing electrode 150 and the steps for assembling the insulating member 132 and the like. FIG. 5 shows the steps in FIG. 4B and FIG. The structure of the rear end side of the insulating member 132 corresponding to 4 (c) is shown. As shown in FIGS. 4B and 5, the rear end face of the insulating member 132 is formed with three conductive portions separated and metalized by three grooves 133, one of which is a glow heater electrode. The extraction part 134 and the other two are the sensor electrode extraction part 135. As shown in FIG. 6, the sensor electrode take-out part 135 is connected to the connection wire 141 from the pressure detection element 40 and to the sensor electrode 42 as shown in FIG. 4C. The The glow heater electrode lead-out portion 134 is connected to the glow energization electrode 150 by a metallized layer formed on the inner peripheral surface of the insulating member 132, and is connected to the glow heater electrode 157, and is electrically drawn out to the rear end side. .

  As shown in FIG. 3, a ring-shaped member 54 is fixed to the peripheral edge portion of the second flange portion 152 of the glow energizing electrode 150 by welding or the like. The front end side of the ring-shaped member 54 is fixed to the rear end side of the heater 20 and is electrically connected to a plus side electrode (not shown) provided so as to be exposed on the outer peripheral surface of the heater 20. , Constituting a part of the power supply path to the heater 20. The ring-shaped member 54 also functions as a pressure transmission mechanism. That is, when the heater 20 is displaced to the rear end side by the combustion pressure, the peripheral edge portion of the second flange portion 152 is pressed via the ring-shaped member 54, and the rod-like portion 156 on the rear end side of the second flange portion 152 is pressed. The center portion of the first flange portion 151 is pressed. At this time, the peripheral portion of the first flange portion 151 is fixed to the housing 1 via the insulating member 132 and the pressure detection element holding cylindrical member 30 as described above, and therefore, the central portion of the first flange portion 151. Is distorted to displace to the rear end side. And the combustion pressure in a combustion chamber is detected by detecting the distortion of the 1st flange part 151 at this time with the pressure detection element 40. FIG. In addition, since it is comprised similarly to the glow plug 100 with a combustion pressure sensor mentioned above about the other site | part, the same code | symbol is attached | subjected to a corresponding part and the overlapping description is abbreviate | omitted.

  In the glow plug 200 with the combustion pressure sensor configured as described above, the combustion pressure can be detected with high accuracy and the size can be reduced as in the case of the glow plug 100 with the combustion pressure sensor described above. .

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment and the like, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.

The figure which shows the whole glow plug with a combustion pressure sensor which concerns on embodiment of this invention, and the cross-sectional structure of the principal part. The figure which shows the cross-sectional structure of the principal part of the glow plug with a combustion pressure sensor which concerns on embodiment of this invention. The figure which shows the cross-sectional structure of the principal part of the glow plug with a combustion pressure sensor which concerns on 2nd Embodiment of this invention. The perspective view which expands and shows the principal part structure of the glow plug with a combustion pressure sensor of FIG. The top view which expands and shows the principal part structure of the glow plug with a combustion pressure sensor of FIG. The top view which expands and shows the principal part structure of the glow plug with a combustion pressure sensor of FIG. The top view which expands and shows the structural example of a pressure detection element typically. The top view which expands and shows the structural example of a pressure detection element typically. The top view which expands and shows the structural example of a pressure detection element typically.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Cap member, 4 ... Screw part, 5 ... Tool engaging part, 6 ... Opening part, 7 ... Sheet surface, 8 ... Connector, 10 ... Heater support member, 11 ...... Housing connection part, 12 ... movable part, 13 ... heater connection part, 20 ... heater, 23 ... tip surface (pressure-receiving surface), 30 ... cylindrical member for holding the pressure detection element, 31 ... flange 32, insulating plate, 33 ... glow electrode through hole, 34 ... element electrode through hole, 35 ... cylindrical body, 40 ... pressure detecting element, 41 ... element electrode, 42 ... sensor Terminal, 43... Signal processing circuit, 44... Substrate, 45 .. IC, 46 .. insulating material, 50 .. glow energizing electrode, 51 .. first flange portion, 52. , 53... Through-hole, 54... Ring-shaped member, 55. 0 ...... combustion pressure sensor glow plug.

Claims (7)

A housing formed in a cylindrical shape;
A pressure sensing element disposed within the housing;
A heater provided such that a front end side protrudes from a front end portion of the housing and a rear end side is accommodated in the housing, the front end surface being a pressure receiving surface, and a heater for transmitting combustion pressure to the pressure detecting element; ,
A conductive member for power supply for supplying power to the heater, which is provided on the rear end side in the axial direction from the heater in the housing and connected to the heater directly or via another member, A power supply conductive member having a pressure detection element mounting portion disposed so as to be orthogonal to the central axis of the heater and having a pressure detection element mounting portion that is distorted by the combustion pressure transmitted by the heater ;
The conductive member for power supply includes the pressure detection element mounting portion on which the pressure detection element is disposed, and a rear side central portion on the opposite side of the pressure detection element mounting portion on which the pressure detection element is disposed. And a rod-shaped portion protruding in the central axis direction of the heater, and the pressure detection element is caused to act on the combustion pressure transmitted by the heater between a peripheral portion of the pressure-detecting element mounting portion and the rod-shaped portion. A glow plug with a combustion pressure sensor characterized by distorting the mounting part . The glow plug with a combustion pressure sensor according to claim 1 ,
A glow plug with a combustion pressure sensor, wherein the pressure detection element is fixed to the pressure detection element mounting portion via an insulating material. The glow plug with a combustion pressure sensor according to claim 2 ,
A glow plug with a combustion pressure sensor, wherein the insulating material is glass. In the glow plug with a combustion pressure sensor of any one of Claims 1-3 ,
The pressure detection element includes a piezoresistor, the piezoresistor is arranged to be point-symmetric with respect to the central axis of the heater, and all the piezoresistors are connected in series. A glow plug with a combustion pressure sensor, wherein the pressure detection element is disposed in the pressure detection element mounting portion. The glow plug with a combustion pressure sensor according to claim 4 ,
The piezoresistors on each side when the piezoresistors arranged so as to be point-symmetric with respect to the central axis of the heater are divided into two by an imaginary line passing through the central axis of the heater and orthogonal to the central axis A glow plug with a combustion pressure sensor, characterized in that the sum of the resistance values of each is equal. The glow plug with a combustion pressure sensor according to any one of claims 1 to 5 ,
The housing has a seat surface in close contact with the engine on the front end side in the axial direction, and a screw portion for engine attachment on the outer peripheral surface on the rear end side in the axial direction from the seat surface.
A glow plug with a combustion pressure sensor, wherein the pressure detection element is provided on the distal end side in the axial direction from the engine mounting screw portion of the housing. In the glow plug with a combustion pressure sensor of any one of Claims 1-6 ,
The glow plug with a combustion pressure sensor, wherein the pressure detection element is disposed on the heater side of the pressure detection element mounting portion.

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